Studies performed in this laboratory have revealed several interesting and unique catalytic features of both AMV and RLV DNA polymerase and Terminal deoxynucleotidyl transferase. Pyridoxal 5' phosphate and phenylglyoxal have been identified as substrate site and template site specific reagents of RTs. Effect of these site specific inhibitors on the catalytic process and mechanism of their interaction with the active site will be fully explored to allow the structure/function relationship of active sites in these enzymes. Structural studies of these sites have become ameanable for analyses due to the fact that both pyridoxal phosphate and phenylglyoxal can be covalently bonded to the site of their action. The major emphasis on the substrate binding site-Pyridoxal phosphate interaction will be to establish location and singularity of lysine residue, that has been found to react with PyP, under different conditions of catalysis. A consistent labeling pattern of peptides will indicate specific labeling of lysine and would permit the isolation of that peptide for amino acid composition and sequence studies. An additional confirmatory analysis will be carried out by labeling that site with photoaffinity labeled analogue of dNTPs. The investigations related to template binding site are designed to determine the 'Unity' of RNase H and template binding site in RT through catalytic and structural studies that utilize an arginine specific reagent, phenylglyoxal as a labeling reagent for that site. Peptide containing this site will be isolated and analysed for amino acid composition and sequence. A complementary study in the form of localization of zinc binding site seek to identify the binding site such that structural analysis of that site could also be performed. The functional analysis of the participation of the individual site through the catalytic study together with the structural studies are expected to clarify mechanics of template dependent and independent synthesis of DNA.